ok i may have figured it out. the dhcp client creates an ipv6 pool, from which you can add an address and specify that pool. not sure if it's dynamic - it's mark is suggesting it's not. it may simply be there to auto fill as putting ::/64 as an ip with the pool specified auto fills the complete /64 in its place

how would I add an additional Mikrotik to this ipv6 network? The existing router gets an ipv6 address from Orcon via dhcp, how would another Mikrotik on the LAN (configured as a bridge) join in on the goodness?